Underreamer



March 8, 192K C. T. MAPES UNDERREAMER Filed NOV. 8,. 1922 Z SheeS-Sh l FIG.

March 8, 1927. L

C. T. MAPES .UNDERREAMER 4 Filed Nov. a, 1922 2 Sheets-Sheet 2 Fl G.. 8

` ZNVENTOFQ BY a v ATTORNEY patented Mar. 8, 1927.,

unirsi) STATES.

rArsNr r r i c i` CLARENCE T. MAPES, F PITTSBURGH, PENNSYLVANIA UNDERREAMER. y

AppIieation led November 8, 1922. Serial No. 599,652.

ple design, eliminating many of the experisive machining operations 'necessary with the manufacture of some underreamers now on the market, but which has greater strength than some other tools of this type now on the market.

Other objects of the invention are to provide a one-piece body construction for the tool, a novel form of actuating mandrel for the cutters, and a novel form of cutter of great strength, all combined to co-act in providing a superior underreamer which may be easily assembled and taken apart.

These and other objects and advantages are attained by my invention, which is illustrated in the accompanying drawings, in which:

Fig. 1 is a side elevation of the assembled tool; 'Y

Fig. 2 is a longitudinal section on a larger scale of the tool shown in Fig. 1, with the eut-ting bits in expanded position;

Fig. 3 is a view similar to Fig. 2, with cutters in collapsed position;

Fig. 4. is a transverse section in the plane of line lV--IV of Fig. 2;

Fig. 5 is an end view of the cutting-end nf the tool; l

Fig. 6 is a side elevation of the cutter actuating mandrel;

Fig. 7 is a fragmentary View, showing the lower end of the cutter in section as in Fig. 2, the section being in the plane of line VH-VU. of Fig. 2; Y' Y Fig. 8 is a section similar to Fig. 7, showing the cutters removedy Fig. 9 is an end view of the lower end of the body with the cutters removed;

Fig. 10 is a section in the plane of line X-X of Fig. 8:

Fig. 11 is a side elevation ofthe two cutters apart from the body;

Fig, 12 is a similaitNiew of the cutters, showing them turned at right angles to the r position in Fig. 11;

Fig. 13 is a perspective view of one of the cutters.

In the drawings, 5 designates a one-piece underreamer body having a threaded connection 6 at its upper end for joining the vbody to a tool string, and at 7, the body is flat-sided for accommodation of a wrench. The portion of the body below part 7 is eylindrical, and comprises the main part of the body.

The lower end of this cylindrical body portion is provided with an` inwardly tapering or conical chamber 8, which is substantially circular at any point in cross-section, a chamber of this shape being readily formed in the body by a lathe operation. At diametrically opposite points in the conical walls of this chamber-and spaced inwardly from the bottom edge, which is continuously circular and without projecting lugs, are two vrecesses or pockets 9. These pockets can be readily formed in the walls of the chamber after the chamber has been machined in the body by a simple milling operation.

As contrasted with the remaining area of the walls of the chamber, the'poclrets do not taper inwardly, as clearly shown in Fig.

They are curved in transverse cross' section, but they are struck on an arc whose `radius is shorter than the radius of the chamber at the point where they are located, as will be apparent rom Fig. 10.

The tapered chamber terminates in the body at shoulder 11, and from this lpoint a longitudinal bore 12 extends for a considerable distance into the body. Passing through the body in a plane at right angles to the recesses 9, and intersecting the. bor l2, are two parallel key slots 13.

The extreme lower end of thev body is preferably beveled outwardly, as designated by 14.

Received within the body is a longitudinally movable mandrel 15 having a circular head 16 on its lower end, above which are two tapered keys 17. A short distance above the head is an enlarged portion 18 which is preferably of "substantially the same diam eter at the bore 12, so that it has a sliding fit therein- The stem of the mandrel above the enlarged portion has Hat faces 19 on two `diametrically opposite sides thereof, and the upper end of the mandrel is threaded at 20 to receive 'a nut 21. Shoulders 18n are formed on the mandrel above the enlarged the part 18 thereof. The nut 2l serves to con ine a compressing spring 22 between it and the shoulders 18H, this spring surrounding the stem of the mandrel.

When the mandrel is in place in the body, it being readily removable therefrom, keys 23 are passed through slots 13 at each side of the mandrel, the keys bearing against the fiat sides 19 of the mandrel to hold it from rotating. rlhese keys are held in place by reason of the slots being tapered toward one end thereof, screws 24; (see Fig'. 4) servingr to hold the keys against reverse movement.

To insert the keys, a pilot key, not shown, but of usual construction, is first driven Vthrough the slots to raise spring 22l oft from shouldersla. The keys 23 follow the pilot keys, .and when inserted form a seat against which the spring reacts for forcing the niandrel upwardly fr the purpose hereinafter described.

The mandrel serves to retain and actuate a pair of opposed cutters, which cutters are designated 25. Each cutter comprises a bit portion 25a and a shank 25".

The bit portion of each cutter has a cutting edge 2G and increases in cross section toward the upper part thereof by reason of curvature of the inner face thereof. This cutter portion terminates at shoulder "27, which is inwardly beveled at 28. The cutter portion is substantially semi-circular in cross section, but it is turned in such manner that the center ot curvature for lower part 29 is different 'from the center ot curvature of upper part 30. In other Words while the periphery of the cutter part is curved to comprise an are of a circle at any point, so as to be' capable ot being formed on a lathe, vet the axis ot rotation about which the cutter is revolved in turning is different in the two parts designated 29 and 30 of the cutter'. The cutter part of the bit is `flattened at 3l, and further flattened or cut away at 32.

As shown in Figs. ll and l2, the shanks of the two cutters, when the cutters are set in expanded osition, form a perfect truncated cone. ltach shank is semi-circular in cross section at any point except where fiatened surfaces 33 are formed on the inner faces of the shanks. When the cutters are expanded, they contact with each other throughout substantially the full area of their opposing faces, except where they are drilled at 34 `to loosely receive the mandrel and countersbored at 34 to receive the head of the mandrel, the faces 33 then being out of contact. 1When the cutters are collapsed, only faces 33 contact. Edges 35 are the edges on which the cutters rock on each other.

The Shanks of the cutters may be turned in a lathe, the peripheries being semi-circaterasse lar, but the anis about which being turned is dierent, and

they rotate in angularly disposed with. relation to the axis about which the major portion ot being turned down.

the cutter is rotated in The upper part of the shank is made to :tit into the recesses 9, and

the end face 36 ot the shank conforms with the shape of and coasts with the end shoulstern of the mandrel up between the critters.

Cut into the channel 3:

the reception of key l? on the in recesses 3ft et the passes The ,top-ends ci? the shank, whenA the bits are collapsed, are received 1n the respective pockets Keys l?" hold the cutters from rotation relatively te the mandrel against shoulders 9a.

and keys 23 hold their" from turning. ll/*hen the cutters lapsed, the ends 36 ci? drei colthe Shanks nlinear With ,the bits in this position, the mandrel is held down with the spring1 22 under coin tion, the exterior body, and faces 33 tact.

pression. ln this posifaces of the cutter part of the bits are within ot the Shanks are in conln order to hold the bits in this posithe diameter of the tion, they mustbe so confined as to hold them from spreading.

ln practice, the well .casing holds them against such expansion.

When the cutters are ineT out of the end of released, as by pass the Casin@` the mandrel l5 is moved upwardly by the spring 22, iniparting a correspondmg motion to 'the bits 25. .ln order for are inclined, and

the bits to siide, faces tl they act with surface 36 of the cutters as cams to throw the Shanks of the bits int bits rocking on each o contact with eachother, the

other at point 35.

V/Then the Shanks yof the bits are thus in contact with each other,

they clear the re cesses 9 and the bits may move further up into the chamber. lThe stantially solid metal Shanks form a subcone which wedges into the tapered chamber, the inner faces et the Shanks bearing a ends of the cham einst each other while the ers form shoulders which abut against shoulder ll, and the outer :taees of the Shanks contact with the conical walls `of the chamber 8,

with, which they contorni.

The beveled faces 28 of the cutters cooper^- 'ate with the beveled end 14 of the body.

The co-aeting to deilect the otherwi thrust of the working ing the spreading or cutter bevel faces le. and 23 serre se unsupported verticali bits inwardly, decreasbursting strain on the cxtreme lower part of the body, and transmit it inwardly, where it the walls the large area of is distributed over et the conical recess away from the end oit the body where the body can withstand it. By reason. of the shanhs of the cutters forming e perfect eene,

held in the tool by ineens The enazular head le et the lill) temeertbe strains are distributed 'over a wide area, instead ot being concentrated at tvvo diametrically opposite points, and the strain is carriedwell up into'the body of the tool, thus counteracting the 4spreading strains on thelower end of the body. The shanks of the cutters being in Contact also transmit strains from the inner` end of one bit to the inner end othe other. The round cross head l@ gives a lull Support to the cutters, while pro-riding a very cheap form of support. rlhe Shanks of the cutters, bein r semicircular, have a large cross section o metal therein, which greatly strengthens the bit.

lVhen the conical Shanks of the cutters are in working position, they act to exclude dirt from the bore and Spring. rlhe circular enlargement 18 also acts to exclude dirt. The spring 22 is so proportioned that, if, in pulling the tool,A the bits 25 should catch instead of immediately collapsing, and the cutters thus be pulled down below the normal eollapsed position of the cutters, the adjacent convolutions of the Spring will make a metal to metal contact, preventing mandrel headl 16 from being pulled down so i'ar as to allow the cutters to fall out. 'lhe only way, therefore, to remove the bits, is to remove keys 23.

As practically all of the shaping ot` Athe body and cutters may be carried out'in a lathe, the tool is extremely simple and economical to make, and the very features that make for economy of manufacture also make :tor increased Strength and duralibity.

l claim as my invention:

l. An underreamer comprising a one-piece body having" a longitudinally extending boro termed in the lower part thcreot' and a bit receiving chamber at the extreme lower part ol'lhe body into which the bore opens, a mandrel .in said bore having a bit engaging head thereon. which extends into the chamber, bits having Shanks thereon, which Shanks extend into the chamber, said bits having recesses therein in which said head engages for supporting the bits, a circular enlargement on said mandrel having a sliding lit in the bore, said mandrel having flat faces formed thereon above the enlargement, keys pasing through the body engaging the tlat sides ot' the mandrel, and a. spring surrounding the mandrel confined between the keys .andi means at the upper end of the mandrel, the wall of said bit-receiving chamber having pockets therein Jfor engagement by the bits in their collapsed condition, and interengaging means between the man.- drel and bits to prevent 'turning et the lat tciindependently of the mandrel so that they .may operate and may be maintained in proper lines with the pockets.

2. .den underreamer includiiiga body having a bore whose lower portion is trusteconical and open and constitutes a bit-receiving chamber, a plurality of bits extendand the bits to maintain the bits in their collapsed condition in line with the pockets' so that they may be freely moved into the latter and 'to prevent rotation of the bits relatively to the mandreland body.

3. An nnderreamer including a body having al central bore and a conical chamber in the lower end of the body, the Wall of the chamber having a pair of opposed pockets' therein, a pair of cutters having Shanks projecting into the said chamber and which t together to form a substantially perfect truncated cone conforming to the said chamber in the body, the said Shanks when the cutters are in operative position making contact with thc conical walls of the chamber over their entire unbroken Surface, said pockets serving to receive the upper end of the Shanks when the cutters are collapsed, and a mandrel non-rotatable relatively to the body for operating the cutters, and

means retaining` the cutters against displacement relatively to the mandrel and accordingly aga-inst rotation relatively to the body.

l. An underreamer including a body having a central bore and a conical chamber in the lowermost cnd'ot1 the body with the larger end ot tho conical chamber terminatingr at the bottom ot thc body, the all ot the clxainbcr having a pair ot opposed re cesscs therein between the upper and lower limits oi the chamber, a pair oli' cutters liar- .ing Shanks projecting into the conical chamber and which fit together to form a Substantially perfect truncated cone contorniing to the conical chamber in the body, the said Shanks when the cutters are in operative position contacting with the conical wall ot' the chamber over its entire unbroken surface, said pockets serving to receive the upper ends of the Shanks when the cutters are collapsed, and means non-rotatable relative to the body for moving the cutters to operative position, and iuterengaging connections between the latter means and cutters to hold the cutters against rotation relative to the body and in proper alignment with respect to the pockets.

n. An underrearrer including a body having aicentral bore and a conical chamber in the lowermost end of the body, with the `larger end f the conical chamber terminating at the bottom of the body, thewall ot' the chamber, having a 'pair of opposed pockets therein between the upper and the lower limits of the chamber and having a.

'lll

continuous beveled lower extremity, a'pair of cutters having Shanks projecting into the conicalcham'ber and which fit together to form a substantially perfect truncated cone conforming to body, the said Shanks when the cutters are in operative position contacting With the conical wall of the chamber over its entire unbroken surface, said pockets serving to receive the upper ends of the Shanks when the cutters are collapsed, said cutters havthe conical chamber in the' ing beveled shoulders 'thereon formed lee-f tween the shank and the body perticn to receive the beveled end of 'the body when the cutters are in operative position, and e mandrel non-rotatehle reletive'tc the iccdy to hold the cutters against rotation relan tively to the body and for opereting'the cutters.

In testimony whereas?.e it @Jn my signe- 2@ ture.

CLARENCE 

